IF the letter code stamped on the front pad is FMC, this block is either:
1985 350CI 165 hp LS-9 700R4 trans 4bbl carb VIN L in a 10, 20, or 30 series with Cal emissions
OR (probably not)
1997 255hp EXPORT L-31 (Vortec) manual trans CK20 or CK30 VIN R